[SLUG] Re: your mail

From: Ian C. Blenke (ian@blenke.com)
Date: Thu Dec 13 2001 - 11:35:00 EST


There are two ways of defining an X11 screen for Unix applications linked
against Xlib:

        $ DISPLAY=:0.0; export DISPLAY # Bourne shells
        $ setenv DISPLAY :0.0 # C shells
and
        $ command -display :0.0

You export/setenv the DISPLAY variable so that child applications spawned
from your shell inherit those variables in their environment.

The key is using the other "screen", by appending a dot and a number to the
display number, ie:

        $ bbkeys -display :0.0 &
        $ bbkeys -display :0.1 &

The colon denotes the beginning of an X11 display.screen declaration. You
can have one display with dozens of screens. The downside to this, of course,
is that you need a window manager that can handle/manage multiple screens.
Another big gotcha is that you can't move windows from one screen to another
(unless, of course, the application is multi-screen aware).

If you omit the .screen portion, .0 is assumed (the first screen). So, the
following are *exactly* the same thing:

        $ bbkeys -display :0
and
        $ bbkeys -display :0.0

When you use a hostname in front of the colon, you are using TCP sockets
for the X11 connection instead of a local Unix Domain Socket:

        $ bbkeys -display localhost:0

This tells Xlib to establish a TCP socket to X11 display zero, which is
TCP port 6000 (X11 uses TCP 6000 + display number).

If you have an X11 app that is *very* bandwidth intensive, it is good to
make sure you're using a Unix Domain socket for your X11 sessions. Just
make sure that there is no "host" portion in front of the colon (":").

Xinerama joins multiple screens into one large virtual screen, so you
only have one screen running on one X11 display. If you have two X11
screens running at 1024x768 as :0.0 and :0.1 for example, running in
Xinerama with the screens located to the left and right of one another
would result in one screen :0.0 that is 2048x768 resolution.

- Ian C. Blenke <ian@blenke.com>

On Tue, Dec 11, 2001 at 01:36:55PM -0800, Justin Keyes wrote:
> I am running blackbox on a dual-headed display. I don't like how
> xinerama works, so I use the option to have 2 "separate" desktops (one
> for each display). When I startx, bbkeys runs on the first display
> because I have
> bbkeys &
> in ~/.xinitrc
> But on the second display, bbkeys won't pick up my keyboard commands
> because of the above "separate desktops" option (which I guess means I
> am
> running two blackboxs and even 2 separate x sessions--although I am not
> sure because I simply chose the option in SuSE's "sax2" X configuration
> program, which doesn't let me in on its inner workings [see, another
> problem with GUI
> front-ends!]). So I have to run another bbkeys on that second
> desktop/display/head.
> My question:
> How do I get bbkeys to start automatically on the _second_
> display/desktop (as
> I have done with the first via ~/.xinitrc)? Thank you very much for your time!
>
> =====
> ________________
>
> Justin Keyes
> m9u35@yahoo.com
> ________________
>
> __________________________________________________
> Do You Yahoo!?
> Send your FREE holiday greetings online!
> http://greetings.yahoo.com

-- 



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